The present disclosure relates to an image processing device, an image processing method, and a program, and, in particular, to a technology of improving precision of detecting obstructive behavior to a monitoring camera.
There has been known a monitoring system in which, in order to find an intruder such as a person and an animal into a predetermined space, an image of space monitored by a monitoring camera is captured, and the intruder is detected based on the captured image. Such a monitoring system is prevented from monitoring when an original direction of the monitoring camera is changed by obstructive behavior. Therefore, it has been proposed to compute a difference between a luminance value of a current image captured by a monitoring camera and a luminance value of a reference image stored beforehand, and to determine that obstructive behavior has occurred when the difference value is equal to or larger than a given value (for example, see Japanese Unexamined Patent Application Publication No. 2008-77517 (JP 2008-77517A)).
However, in a technique disclosed in JP 2008-77517A, among images inputted by the monitoring camera frame by frame, for example, an image obtained every other frame may be stored as a reference image and updated sequentially. When no obstructive behavior has occurred and a subject in the captured image does not move, a temporally-previous background image and a temporally-subsequent background image are substantially the same. Therefore, the difference between the luminance values in these images is also small.
In contrast, when the direction of the monitoring camera is changed by obstructive behavior, the temporally-previous background image and the temporally-subsequent background image are different. Therefore, the difference between the luminance value of the current image and that of the reference image is large. For this reason, when the difference between the luminance value of the current image and that of the reference image is large, it is determined that obstructive behavior has occurred. The difference between the luminance values may be calculated for the entire image, but is typically calculated for each of a plurality of divisional regions obtained by dividing a region of an image into a predetermined number of regions in many cases.